Coating compositions, such as paints and varnishes, have been known for a long time. Their possible applications are diverse; one need only consider large metal structures, such as ships, railroad wagons, industrial plant, bridges, or other constructions with substantially smooth surfaces which require protection against the effect of weathering, corrosion or soiling, e.g., graffiti.
Examples of known systems include silane-based radiation-crosslinking systems and also thermosetting systems (EP-A 0 424 645, EP-A 0 408 047). The curing of such coatings requires a UV or electron beam source or an oven, of appropriate size.
Coating systems based on silicon resin are known (EP-A 0 670 870). The coating systems provided are constructed based on silicone resins and aminosilanes. Silicone resin, likewise, is often inappropriate because of cost, and cannot be used in a large number of applications, since they require many different types of resin and grades.
Two-component systems have also been described (WO 96/16109). In these systems, the silane is used both in the binder and in the curing component. However, two-component systems of this kind are inappropriate, since they are complicated and have poor storage properties. Moreover, there is no guarantee that, on site, the components will be mixed in the correct proportions.
A one-component system has been described in, for example, EP-A 0 786 499. This moisture-crosslinking composition is composed of at least one polyfunctional acrylate, at least one titanium or silicon ester, and a higher fraction of at least one amino-functional trialkoxysilane. In this system only acrylic resin can be used. This greatly restricts the flexibility of the coating to expand the possibilities for use.
Furthermore, the coatings of the above systems have adequate adhesion only on materials such as glass, wood, polycarbonate, polyethylene, polypropylene, polyethylene terephthalate, and polystyrene. The adhesion to steel and other materials, such as aluminum, is much less.
Additionally, coatings based on aminosilanes often have poor water stability and poor adhesion following water treatment. The coatings ought also to have properties such as scratch resistance and water resistance.
Therefore, there is a need in the art for compositions, which can be used as coating that provide good adhesion to a variety of substrates, with ease of use, and provide good resistance to, for example, scratches and water.